I have some hundred (user) tables where only a small subset of them requires a more aggressive autovacuum. Setting table level parameters on this small subset seems more straightforward to me. Loosing this setting on pg_dump / pg_upgrade would be ok for me. Doesn't happen that often.
I tried this on postgres 9.6: postgresql.conf -> allow_system_table_mods=on + pg_ctl restart # alter table pg_catalog.pg_shdepend set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 1000); ERROR: shared tables cannot be toasted after initdb Time: 0.618 ms # alter table pg_catalog.pg_largeobject set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 1000); ERROR: AccessExclusiveLock required to add toast table. Time: 0.590 ms # alter table pg_catalog.pg_largeobject_metadata set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 1000); ERROR: AccessExclusiveLock required to add toast table. Time: 1.601 ms Any idea? Thanks, Markus Von: Zwettler Markus (OIZ) <markus.zwett...@zuerich.ch> Gesendet: Freitag, 4. Juni 2021 17:44 An: Vijaykumar Jain <vijaykumarjain.git...@gmail.com> Cc: pgsql-general@lists.postgresql.org Betreff: AW: [Extern] Re: autovacuum on pg_catalog tables Thanks for the info. I have a lot of LO manipulation and want a more aggressive autovacuum on some pg_catalog tables therefore. I do not see any reason why this should not work or be at risk? Markus Von: Vijaykumar Jain <vijaykumarjain.git...@gmail.com<mailto:vijaykumarjain.git...@gmail.com>> Gesendet: Freitag, 4. Juni 2021 17:37 An: Zwettler Markus (OIZ) <markus.zwett...@zuerich.ch<mailto:markus.zwett...@zuerich.ch>> Cc: pgsql-general@lists.postgresql.org<mailto:pgsql-general@lists.postgresql.org> Betreff: [Extern] Re: autovacuum on pg_catalog tables ok, what i am sharing, DO NOT DO IT. it is just to answer why it is not working :) PostgreSQL: Documentation: 13: 19.17. Developer Options<https://www.postgresql.org/docs/current/runtime-config-developer.html> postgres=# alter table pg_catalog.pg_largeobject_metadata set (AUTOVACUUM_VACUUM_COST_DELAY = 1); ERROR: permission denied: "pg_largeobject_metadata" is a system catalog postgres=# show allow_system_table_mods; allow_system_table_mods ------------------------- off (1 row) postgres=# set allow_system_table_mods TO 1; SET postgres=# show allow_system_table_mods; allow_system_table_mods ------------------------- on (1 row) postgres=# alter table pg_catalog.pg_largeobject_metadata set (AUTOVACUUM_VACUUM_COST_DELAY = 1); ALTER TABLE but you can always run vacuum manually on the table. vacuum (verbose,analyze) pg_catalog.pg_largeobject_metadata; INFO: vacuuming "pg_catalog.pg_largeobject_metadata" INFO: index "pg_largeobject_metadata_oid_index" now contains 0 row versions in 1 pages DETAIL: 0 index row versions were removed. 0 index pages have been deleted, 0 are currently reusable. CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s. INFO: "pg_largeobject_metadata": found 0 removable, 0 nonremovable row versions in 0 out of 0 pages DETAIL: 0 dead row versions cannot be removed yet, oldest xmin: 8083775 There were 0 unused item identifiers. Skipped 0 pages due to buffer pins, 0 frozen pages. 0 pages are entirely empty. CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s. INFO: analyzing "pg_catalog.pg_largeobject_metadata" INFO: "pg_largeobject_metadata": scanned 0 of 0 pages, containing 0 live rows and 0 dead rows; 0 rows in sample, 0 estimated total rows VACUUM On Fri, 4 Jun 2021 at 20:10, Zwettler Markus (OIZ) <markus.zwett...@zuerich.ch<mailto:markus.zwett...@zuerich.ch>> wrote: I would like to start a more aggressive autovacuum on pg_catalog tables like pg_largeobject. So I tried as a superuser: # alter table pg_catalog.pg_largeobject_metadata set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 5000); ERROR: permission denied: "pg_largeobject_metadata" is a system catalog (How) Is it possible to change such table attributes on pg_catalog tables? Thanks, Markus -- Thanks, Vijay Mumbai, India Achtung: Diese E-Mail wurde von einer externen Adresse verschickt. Klicken Sie auf keine Links und öffnen Sie keine angehängten Dateien, wenn Sie den Absender bzw. die Absenderin nicht kennen. Sind Sie sich unsicher, kontaktieren Sie den Service Desk der Stadt Zürich.
